Still reachable in valgrind

While searching about still reachable in valgrind, some people say its not a problem. we don't nedd to fix it. Some people say it needs to be fixed.I would be better if somebody could exaplain me explicitly what is the logic behind this still reachable. Is it mandatory to fix this?

[EDIT]

У меня есть следующие выходные данные valgrind для моей программы на C. Нужно ли мне это исправить?

      LEAK SUMMARY:
      ==27333==    definitely lost: 0 bytes in 0 blocks.
      ==27333==      possibly lost: 0 bytes in 0 blocks.
      ==27333==    still reachable: 96 bytes in 12 blocks.
      ==27333==         suppressed: 0 bytes in 0 blocks.